What is vertical spoilers, Mechanical Engineering

Q. What is Vertical Spoilers?

Vertical Spoilers - Use a three-start system of short vertical spoilers arranged in a helical pattern on the top third of the vessel. The exposed width beyond insulation of the spoilers should be 0.09D, and the pitch between 5D and 11D. There should be a minimum of 8 spoilers over the pitch distance (each complete helical wrap), and a minimum of 1.5 helical wraps over the top third of the vessel. The spoiler system may be interrupted to provide clearance at vessel appendages.